You can create a 'default value' in one of two forms.

<p>1. Java LocalDate or LocalDateTime code style</p>
<ul>
    <li>LocalDate.now();</li>
    <li>LocalDate.now().plusDays(1);</li>
    <li>LocalDate.now().plusDays(1).plusYears(2);</li>
    <li>LocalDate.now().minusDays(5).minusMonths(3).minusYears(2);</li>
    <li>LocalDateTime.now()</li>
    <li>LocalDateTime.now().minusHours(5).plusMinutes(10).minusSeconds(20);</li>
    <li>LocalDateTime.now().minusDays(5).plusYears(5).plusSeconds(50);</li>

</ul>

<p>2. LocalDate String (This case should match the format of 'dateFormat')</p>
<ul>
    <li>20170501</li>
    <li>2017-05-01</li>
</ul>